Inspect Manual

Using Inspect With Accelerated Programs on TNS/R
Systems
Inspect Manual—429164-006
16-9
Data Breakpoints
Usage Considerations for Accelerated Programs

The INFO LOCATION command marks statement locations at which breakpoints
cannot be set as “deleted.”

When the LOCATION FORMAT command is set to STATEMENTS, statement
ordinals for statements at which breakpoints cannot be set are emitted when
displaying program source. For more information, see SOURCE on page 6-196.

The SOURCE command marks deleted statements with a “-”.
Data Breakpoints
Data breakpoints, also referred to as memory access breakpoints (MABs), are
available on TNS/R systems, but there are some important considerations when you
use them with accelerated programs.
Data breakpoints, also referred to as memory access breakpoints (MABs), are
available on TNS/R systems.
On all systems, the default type of data breakpoints is changed from WRITE to
CHANGE. Change data breakpoints are like write breakpoints, except that they are
only reported when the value of the variable changes.
WRITE breakpoints are not supported on TNS/R machines.
Data breakpoints may behave differently when debugging programs on a TNS/R
system, especially if the program has been accelerated.
The following considerations apply when using data-breakpoints with accelerated
programs.

There is a four TNS/R instruction delay between when data breakpoints are
detected and reported.
This may result in the current program location being different from the location at
which the breakpoint was detected. When this is the case, the MEMORY ACCESS
BREAKPOINT event string is followed by “OCCURRED AT src-loc.“

The hardware sets data breakpoints on 32-bit words. With 16-bit variables, an
access to an adjacent variable may therefore trigger an unrelated breakpoint.
GUARDIAN is able to filter some but not all unrelated breakpoints.
When CHANGE breakpoints are set, unrelated breakpoints are filtered by Inspect.
When READ/WRITE breakpoints are set, you must use program context
information to determine which breakpoints are related to the data of interest. i
Note. Note that “deleted” does not mean that the actions of your statements have
been deleted, but that optimization has merged the statement with another which
resulted in the statement not being available for debugging.